By David Roberts – Updated March 24, 2022
Oil is a resilient resource; it can endure thousands of years in a stable form. Even after it has been refined and used in vehicles for only a few thousand miles, the same refining principles that produce high‑quality fuels from crude oil can be applied to recycle used motor oil. According to Dr. David Layzell, a scientist at Dominion Oil Refining, re‑refining used oil is often simpler than initial crude refining, and several industrial‑grade systems have been developed to accomplish this.
Transfer the used oil into a high‑temperature chamber and allow it to settle for 1–2 days. During this time, water and solid contaminants rise to the surface. Heat the chamber to 248 °F (125 °C); the water and solids vaporise, leaving the oil dehydrated.
Attach distillation pipes to the top of the high‑temperature chamber and run them at a slight downward angle toward the cooling chamber. For rapid condensation, insert the pipe’s lower end into a container of cool water.
Raise the chamber temperature to 104 °F (40 °C). Vapour rises into the pipes and condenses in the cooling chamber. Carefully decant the gasoline layer; you’re now ready to extract kerosene.
Increase the temperature to 500 °F (260 °C) and repeat the distillation. Kerosene vapour condenses and collects in the cooling chamber. Pour off the kerosene, then refill the chamber with a small amount of water for the next stage.
Raise the temperature to the diesel boiling point, approximately 626 °F (330 °C). Vapour travels upward, condenses in the coil, and settles in the cooling chamber. Diesel rises above the water and is decanted. Transfer this diesel into a clean high‑temperature chamber and repeat the step to further purify the fuel.
Heat the system to 752 °F (400 °C) to distil the remaining heavy fractions. The condensed material can be refined into high‑grade lube oil.
Allow the chamber to cool, then pour off the remaining content. This thick, tar‑like sludge can be repurposed as a construction material or road base.
Safety Note: Distillation involves high temperatures and flammable vapours. Conduct all operations in a well‑ventilated area, use flame‑resistant gloves, and keep fire extinguishing equipment nearby.
